Quote from: vincenzo on Today at 09:04:08 AM

However, from a technological standpoint, nothing precludes to have the "Recovery Server" handled by the user him/herself. In this case, the user is sure that s/he is in full control (having 2 pieces of information out of 3), and it still allows for emergency recovery (e.g., in case of inheritance) with the "Service Provider" if the "Recovery Server" is given to the heirs.

I did consider this use case, but it seems to be in direction contradiction to what you are proposing to solve, that being the risks and dangers surrounding self custody of private keys as you state in your very first paragraph. With this set up, with the user holding 2 of the 3 key parts themselves, they still run the risk of mismanaging their keys and losing access to their funds.

I suppose it could be a better replacement to 2FA that we see with some set ups, such as Electrum and TrustedCoin, in that the final transaction would be smaller and therefore cheaper, as well as not being obviously identifiable as a multi-sig transaction.